To be specific, Chapter 31 of the manga was released a week ago, and yeah Volume 7 will be released soon which will contain chapters 25-28. But still, the manga has only gotten into the bulk of the storyline, and since this is a monthly serialization not much will get done in the manga between now and the completion of the anime, which is why there'll probably be a different ending of sorts.

Actually 31 was released back on the 10th. I don't think there's ever been a Gangan released after the 15th of any month.
Volume 6 already included chapter 25 (because volume 5 had 5 chapters instead of 4), so I figure volume 7 will have 26-29 plus the recent gaiden from the Gangan Powered that was released a little while back.

Anyway, I can invision a few things happening.
Like I said before, Arakawa already planned out that the manga would go on for 20 years (yes, that's 20 years of serialization, not 20 years in the manga) in an old interview in Puff. I figure Bones would at least consult with him a little bit on that.

Of course, things will turn out differently.
Originally, Pinako was supposed to be a guy, the whole Rush Valley arc was written because Arakawa's editor wanted to have more stories focussed on Winry, etc.
I don't think it'll be as bad as something as the Mankin anime, though.